The presence of metals in oils of vegetable or animal origin is known to have deteriorating effect on the stability of these oils. Therefore, oils are often treated with a metal chelating agent, such as citric acid or phosphoric acid, in order to remove such metals.
Often vegetable or animal oils and fats are used as blends in order to show the right physical and chemical properties for a given application. Furthermore the oils or blend of oils have to be further processed in order to obtain suitable properties (e.g., melting profile, mouth feel etc.). The melting profile is often adjusted by rearranging or redistributing the fatty acids on the glycerol backbone either chemically or enzymatically. This process is often referred to as “interesterification”. Enzymatic interesterification is carried out using a lipase.
A disadvantage of adding a metal chelating agent to oil is that it has a negative effect on lipase interesterification performance.